-
Archives of Microbiology May 2016In a study where the prevalence of Aeromonas in shellfish was analysed, three isolates of Aeromonas schubertii were identified, representing this the first report of... (Review)
Review
In a study where the prevalence of Aeromonas in shellfish was analysed, three isolates of Aeromonas schubertii were identified, representing this the first report of this species from mussels. This species was originally described in 1988 from strains isolated from extra-intestinal human infections and since then has been cited in only 18 occasions. For many years, A. schubertii was the only mannitol-negative species of the genus. However, three additional mannitol-negative species (Aeromonas simiae, Aeromonas diversa and Aeromonas australiensis) have been described. This, together with the fact that A. schubertii is a rare human pathogenic species, motivated the present study to characterize its biochemical behaviour and differentiation from the other mannitol-negative species. The molecular similarity (16S rRNA, rpoD and gyrB genes) of the strains, presence of virulence genes and antimicrobial resistance were determined. All A. schubertii strains showed the same phenotypic behaviour, i.e. they use citrate, are positive for lysine decarboxylase and DL-lactate, but negative for production of mannitol, indole and acid from sucrose and could be easily differentiated from other mannitol-negative species. All strains carried the aerA and lafA virulence genes and showed susceptibility to all antibiotics tested. Seafood could be a transmission route of this bacterium to humans.
Topics: Aeromonas; Animals; Anti-Bacterial Agents; Bivalvia; Carboxy-Lyases; Citric Acid; DNA Gyrase; DNA-Directed RNA Polymerases; Food Microbiology; Humans; Lactic Acid; RNA, Ribosomal, 16S; Sigma Factor; Species Specificity
PubMed: 26825089
DOI: 10.1007/s00203-016-1189-5 -
Microbial Pathogenesis Dec 2020Retrospective diagnosis of a bacterial collection (n = 31) originated from five farms reportedly affected by early mortality syndrome (EMS) in Southeast Asia in 2016...
Retrospective diagnosis of a bacterial collection (n = 31) originated from five farms reportedly affected by early mortality syndrome (EMS) in Southeast Asia in 2016 revealed that 9/31 isolates from two farms tested positive for V. parahaemolyticus causing acute hepatopancreatic necrosis disease (VP). Molecular analysis of the 22 remaining isolates showed that 21 isolates belong to Vibrio species including VP, V. vulnificus, V. cholerae, V. owensii and V. alginolyticus. One isolate from an AHPND farm was preliminarily identified as Aeromonas schubertii based on 99.43% nucleotide identity of 16S rRNA to the reference strain ATCC 43700 (X60416). Diseases caused by Vibrio bacteria have been well-studied in shrimp while pathogenic potential of non-Vibrio species has been relatively overlooked. Since the description of A. schubertii present in shrimp farms is rare, this study therefore focused on species identification and its pathogenic potential to shrimp based on a combination of multiple approaches i.e. multilocus sequence analysis (MLSA), challenge test, histopathology and in situ hybridization (ISH). Based on MLSA of 2464 bp derived from 16S rRNA (1346 bp), gyrB (568 bp) and rpoB (550 bp), this isolate was confirmed as A. schubertii. Immersion challenge using three successive 10-fold serial dilutions (2 × 10 to 2 × 10 CFU/mL) revealed that A. schubertii was pathogenic to shrimp and cumulative mortalities were dose-dependent (45-70%). The diseased shrimp exhibited gross sign of reddish body and remarkable histopathological lesion of collapsed hepatopancreatic tubules and typical encapsulation. ISH using A. schubertii-specific probe confirmed localization of bacteria in the hepatopancreas of the infected shrimp. In summary, this study reported a novel pathogenic, non-Vibrio species, A. schubertii recovered from an AHPND-affected farm causing up to 70% mortality in immersion challenge. Since A. schubertii is relatively new to shrimp, this may pose a potential risk for low salinity shrimp farming areas, active surveillance of this pathogen, therefore, should not be overlooked.
Topics: Aeromonas; Animals; Penaeidae; RNA, Ribosomal, 16S; Retrospective Studies; Vibrio; Vibrio parahaemolyticus
PubMed: 32950638
DOI: 10.1016/j.micpath.2020.104501 -
Journal of Clinical Microbiology Aug 1988In 1983 the vernacular name Enteric Group 501 was coined for a group of strains that had been referred to our laboratory as "possible Vibrio damsela that does not...
In 1983 the vernacular name Enteric Group 501 was coined for a group of strains that had been referred to our laboratory as "possible Vibrio damsela that does not require NaCl for growth." By DNA-DNA hybridization (hydroxyapatite method, 32P, 60 and 75 degrees C), six strains of Enteric Group 501 were closely related to the labeled strain 2446-81 (70 to 95% at 60 degrees C and 71 to 93% at 75 degrees C; 0 to 1% divergence). Type strains of all Aeromonas species and reference strains of six other Aeromonas DNA hybridization groups were 26 to 42% related (60 degrees C) to strain 2446-81, but type strains of 27 Vibrio and Photobacterium species, including V. damsela, were 0 to 1% (75 degrees C) related. We propose the name Aeromonas schubertii for the highly related group of seven strains formerly known as Enteric Group 501. The type strain is designated as ATCC 43700 (CDC 2446-81). Strains of A. schubertii grew well at 36 degrees C and had positive reactions at this temperature for methyl red, Voges-Proskauer (1% NaCl, Coblentz method), lysine decarboxylase, arginine dihydrolase, motility, lipase, DNase, nitrate reduction to nitrite, oxidase, and growth in nutrient broth with 0 and 1% NaCl. There was no growth in 6% NaCl or on thiosulfate-citrate-bile salts-sucrose agar. The following sugars were fermented: D-glucose, D-galactose, maltose, D-mannose, and trehalose. The following sugars were not fermented: adonitol, L-arabinose, D-arabitol, cellobiose, dulcitol, erythritol, myo-inositol, lactose, D-mannitol, melibiose, alpha-CH3-D-glucoside, raffinose, L-rhamnose, salicin, D-sorbitol, sucrose, and D-xylose. Esculin was not hydrolyzed, and the string test was negative. The mannitol-negative reaction differtiates A. schubertii from other Aeromonas species. The antibiogram of this organism is typical of other Aeromonas strains (resistance to ampicillin and carbenicillin and susceptibility to most other agents). A. schubertii strains have been isolated from abscesses (two strains), wound (one), skin (one), pleural fluid (one), and blood (two). The two blood isolates suggest clinical significance typical of other Aeromonas species , but further information is needed on this group.
Topics: Aeromonas; Anti-Bacterial Agents; Bacterial Infections; DNA, Bacterial; Humans; Mannitol; Nucleic Acid Hybridization; Phenotype; Terminology as Topic
PubMed: 3139706
DOI: 10.1128/jcm.26.8.1561-1564.1988 -
Microbiology Resource Announcements Jan 2022Aeromonas schubertii is a Gram-negative, rod-shaped bacterium. It is a rare species that has been reported in humans and aquatic animals. Here, we report the genome...
Aeromonas schubertii is a Gram-negative, rod-shaped bacterium. It is a rare species that has been reported in humans and aquatic animals. Here, we report the genome sequences of A. schubertii strains isolated from two mass mortality events in central Thailand that were associated with aquaculture of Asian seabass.
PubMed: 34989613
DOI: 10.1128/mra.01007-21 -
Journal of Fish Diseases Jan 2019Aeromonas schubertii is a major epidemiological agent that threatens cultured snakeheads (Channidae) and has caused great economic losses in fish-farming industries in...
Aeromonas schubertii is a major epidemiological agent that threatens cultured snakeheads (Channidae) and has caused great economic losses in fish-farming industries in China in recent years. In present study, a specific TaqMan minor groove binder (MGB) probe fluorescence real-time quantitative PCR (qPCR) assay was developed to rapidly detect and quantify A. schubertii. A pair of qPCR primers and a TaqMan MGB probe were selected from the rpoD gene, which were shown to be specific for A. schubertii. A high correlation coefficient (R = 0.9998) in a standard curve with a 103% efficiency was obtained. Moreover, the qPCR method's detection limit was as low as 18 copies/μl, which was 100 times more sensitive than that of conventional PCR. The detection results for the A. schubertii in pond water and fish tissue were consistent with those of the viable counts. Bacterial load changes detected by qPCR in different tissues of snakeheads infected with A. schubertii showed that the gills and intestines may be the entry for A. schubertii, and the spleen and kidney are major sites for A. schubertii replication. The established method in present study should be a useful tool for the early surveillance and quantitation of A. schubertii.
Topics: Aeromonas; Animals; Bacterial Load; DNA Primers; Fish Diseases; Fishes; Fluorescence; Gram-Negative Bacterial Infections; Ponds; Real-Time Polymerase Chain Reaction; Sensitivity and Specificity; Water Microbiology
PubMed: 30474192
DOI: 10.1111/jfd.12911 -
Pathogens (Basel, Switzerland) Aug 2021is the etiological pathogen of internal organ nodules in snakehead fish. Infections with produce a significant economic loss in aquaculture. Therefore, it is important...
is the etiological pathogen of internal organ nodules in snakehead fish. Infections with produce a significant economic loss in aquaculture. Therefore, it is important to examine the immune mechanisms by which snakeheads defend against infection. In this study, we established a hybrid snakehead infection model by intraperitoneal injection of that produced internal organ nodules. The splenic immune response of infected fish was examined at the transcriptome level by Illumina-seq analysis. Results showed 14,796 differentially expressed genes (DEGs) following infection, including 4441 up-regulated unigenes and 10,355 down-regulated unigenes. KEGG analysis showed 2084 DEGs to be involved in 192 pathways, 14 of which were immune-related. Twelve DEGs were used to validate quantitative real-time PCR results with RNA-seq data. Time-course expression analysis of six genes demonstrated modulation of the snakehead immune response by Furthermore, transcriptome analysis identified a substantial number of DEGs that were involved in the apoptosis signaling pathway. TUNEL analysis of infected spleens confirmed the presence of apoptotic cells. This study provided new information for a further understanding of the pathogenesis of in snakeheads, which can be used to prevent and possibly treat infections.
PubMed: 34451461
DOI: 10.3390/pathogens10080997 -
Applied Biochemistry and Biotechnology Apr 2014In this study, chitinase activity in an incubation broth of Aeromonas schubertii was measured using colloidal chitin azure as the substrate. More specifically, the...
In this study, chitinase activity in an incubation broth of Aeromonas schubertii was measured using colloidal chitin azure as the substrate. More specifically, the induction of chitinases due to amendment with various carbon sources was examined. The highest chitinase activity was found following amendment with 0.5-1.0 % chitin powder, whereas the activity increased negligibly due to amendment with other carbon sources, such as glucose, GlcNAc, GlcN, sorbitol, sucrose, cellulose, or starch. The chitinase activity induced by the chitin powder was suppressed when the glucose, GlcNAc, GlcN, or starch was added simultaneously to the medium but was not suppressed by the addition of sorbitol, sucrose, or cellulose. The activity of chitinase in the crude extract was also not directly inhibited by glucose. Taken together, these findings suggest that the induction of chitinase activity depends on the acquisition of suitable carbon sources from the environment and that induction occurs at a regulatory level.
Topics: Aeromonas; Biotechnology; Carbon; Chitin; Chitinases; Enzyme Induction; Gene Expression; Glucose; Particle Size
PubMed: 24682877
DOI: 10.1007/s12010-014-0798-1 -
Infection and Immunity May 1992We investigated the phenotypic, structural, and pathogenic properties of 11 Aeromonas schubertii strains recovered from extraintestinal sites. Most A. schubertii strains...
We investigated the phenotypic, structural, and pathogenic properties of 11 Aeromonas schubertii strains recovered from extraintestinal sites. Most A. schubertii strains were autoagglutination positive, possessed a high surface charge but low hydrophobicity, and fell into one or two biogroups on the basis of carbon substrate utilization patterns. Fatty acid methyl ester analysis of A. schubertii revealed this species to contain a relatively high percentage of branched fatty acids (i-13:0, i-15:0, i-17:1, i-17:0) compared with A. hydrophila. Immunologic and biochemical analysis of the lipopolysaccharides of A. schubertii strains allowed for two groups to be distinguished, namely, (i) a collection of six strains belonging to serogroup O:11 that possessed a characteristic homogeneous O polysaccharide side chain profile by silver staining and immunoblotting techniques and (ii) a second antigenically diverse group (five strains) that either exhibited a heterogeneous side chain profile or were side chain deficient. A, schubertii O:11 strains were all found to contain a 55-kDa major protein associated with the outer membrane fraction which was glycine-hydrochloride extractable; non-O:11 strains did not harbor a similar protein molecule. Screening of A. schubertii strains for reputed virulence factors indicated (i) that slightly more than half of the isolates produce an apparent contact-dependent hemolysin that is not cell associated or released extracellularly, (ii) a potent cytotoxin active against HEp-2 cells that is devoid of hemolytic activity, and (iii) lack of enterotoxigeniclike activity as determined by suckling mouse assays. All A. schubertii strains were pathogenic for mice as determined by 50% lethal dose assays, although no single factor correlated with mouse pathogenicity.
Topics: Aeromonas; Bacterial Proteins; Fatty Acids; Hemolysis; Humans; Lipopolysaccharides; Virulence
PubMed: 1563798
DOI: 10.1128/iai.60.5.2075-2082.1992 -
Molecular Immunology Sep 2021As a proinflammatory cytokine of the interleukin-1 (IL-1) family, IL-18 plays important roles in host protection against bacterial, viral, and fungal infection. We...
As a proinflammatory cytokine of the interleukin-1 (IL-1) family, IL-18 plays important roles in host protection against bacterial, viral, and fungal infection. We cloned the open reading frame of snakehead (Channa argus) IL-18 (shIL-18) and found that it contained 609 base pairs and encoded 202 amino acid residues. The shIL-18 included a conserved IL-1-like family signature and two potential IL-1β-converting enzyme cutting sites; one was conserved in all analyzed IL-18s, but the other was unique to shIL-18. Unlike other IL-18s, shIL-18 also contained a predicted signal peptide. In this study, shIL-18 was constitutively expressed in all tested tissues, and its expression was induced by Aeromonas schubertii and Nocardia seriolae in the head kidney and spleen in vivo and by lipoteichoic acid, lipopolysaccharides, and polyinosinic-polycytidylic acid in head kidney leukocytes in vitro. Moreover, recombinant shIL-18 upregulated the expression of interferon-γ, IL-1β, and tumor necrosis factor-α1 and -α2 and promoted the proliferation of leukocytes. Taken together, these results showed that IL-18 played crucial roles in host defense against bacterial infection in fish, as it does in mammals.
Topics: Aeromonas; Animals; Cloning, Molecular; Fish Diseases; Fish Proteins; Fishes; Gram-Negative Bacterial Infections; Head Kidney; Interleukin-18; Lipopolysaccharides; Nocardia; Nocardia Infections; Spleen; Teichoic Acids
PubMed: 34280771
DOI: 10.1016/j.molimm.2021.07.013 -
International Journal of Biological... Aug 2014Chitin derivatives, such as those with modified main saccharide chains and deacetylated side chains, exhibit versatile biological functions. The biomedical properties of...
Chitin derivatives, such as those with modified main saccharide chains and deacetylated side chains, exhibit versatile biological functions. The biomedical properties of chitin oligosaccharides depend on their degree of oligomerization. Of the chitin oligosaccharides, chitin hexamers are generally the most potent. In our recent study, N-acetylchitohexaose was obtained by digesting chitin with ASCHI61, a chitinase from Aeromonas schubertii. In this work, the factors involved in the production of chitin hexasaccharide were evaluated experimentally. Using steep map analysis and cross-analysis, the substrate concentration and reaction pH were identified as the key factors in this reaction, and the interactions between these parameters were observed. Using a response surface experimental design, we predicted that a colloidal chitin concentration of 3.4mgmL(-1) and a pH of 6.54 were the optimal conditions for producing hexaoligochitin. These conditions were verified in separate experiments, in which 38.73mmolL(-1) of N-acetylchitohexaose was obtained. The maximum amount of hexamer produced was 42.175mgL(-1), an increase of only 0.27% from the predicted value.
Topics: Aeromonas; Chitin; Chitinases; Colloids; Hydrogen-Ion Concentration; Kinetics; Models, Theoretical; Polymerization; Temperature
PubMed: 24854211
DOI: 10.1016/j.ijbiomac.2014.05.028